The formation of ultrathin layers of semiconductor heterostructures (on the order of 50 to 400 .ANG. for (Al,Ga)-As/GaAs) leads to the quantization of confined carriers. Such ultrathin heterostructures, which usually comprise alternating layers of dissimilar semiconductor materials, are referred to as superlattices or quantum well structures. The energy band diagram for such structures evidences abrupt steps in the energy gap which form potential wells in the conduction and valence bands, as is well-known. Appropriate selection of materials, compositions and layer thicknesses permits fabrication of unique electro-optic devices.
The use of optics to perform signal processing is attractive because of the high speed of light and the opportunity of using many parallel channels, which yield the promise of very high throughput rates. However, a major obstacle to the realization of this goal has been the lack of a real-time, reliable, high performance spatial-light-modulator (SLM). This lack is largely due to the limitations of materials.